1. Field of the Invention
The present invention relates to a terminal structure of a connecting terminal to be used for connection in an electric system of an automobile. More specifically, it relates to a structure of the vicinity of a contact piece of a connecting terminal to be contacted with a substrate in an electric connection box so as to be conducted and connected.
2. Related Art
Conventionally, as the structure in the vicinity of a contact piece of a connecting terminal, various ones have been known. For example, a connecting terminal 31 shown in FIG. 9 is a female type connecting terminal comprising an electric wire caulking portion 32 and a core wire caulking portion 33 in the rear part, and a plate spring-like elastic contact piece 35 to be contacted with a counterpart conductor portion for electric connection, elongating from a front end fold back portion 34 projecting from a terminal bottom plate 36 in the front part. The elastic contact piece 35, in general, is covered with a top plate 38 supported by side plates 37 provided upright on the terminal bottom plate 36. By forcing and holding a counterpart conductor portion with the top plate 38, an electric connection state can be obtained.
In the connecting operation of the connecting terminal 31 with the above-mentioned configuration, a counterpart male type conductor portion is introduced from the front part, guided by the front end fold back portion 34 and the top plate 38 while forcing the elastic contact piece 35. At the time, the elastic contact piece 35 and the front end fold back portion 34 are deflected so as to hold the counterpart conductor portion with the top plate 38 for achieving the electric connection.
However, according to the conventional connecting terminal 31, when the counterpart male type conductor portion is introduced from the front part, guided by the front end fold back portion 34 and the top plate 38 while forcing the elastic contact piece 35, the elastic contact piece 35 and the front end fold back portion 34 are deflected, and finally the counterpart conductor portion is held with respect to the top plate 38. In this case, since the deflected portions are only the elastic contact piece 35 and the front end fold back portion 34, the distributed load value with respect to the deflection amount is relatively large. With the progress of the introduction of the counterpart conductor portion, the resistance force becomes larger and larger. Accordingly, a problem is involved in that the operativity in the connecting operation is deteriorated.
Further another example of conventional connecting terminal will be described. As the structure in the vicinity of a contact piece of a connecting terminal to be contacted with a substrate in an electric connection box for electric connection in an electric system of an automobile so as to be conducted and connected, various ones have been known. For example, a connecting terminal 131 shown in FIG. 10 is a contact piece exposed type connecting terminal comprising an electric wire caulking portion 132 and a core wire caulking portion 133 in the rear part, and a plate spring-like elastic contact piece 134 to be contacted with a counterpart conductor portion (not illustrated) for electric connection, elongating from a front end fold back portion 135 projecting from a terminal bottom plate 136 in the front part. Deflection preventing pieces 139 are provided below the elastic contact piece 34 by bending the upper end portion of both side plates 138 provided upright from both side ends of the terminal bottom plate 136.
The connecting terminal 131 can be stored in a predetermined connector housing so as to be contacted with a bus bar end portion or a predetermined position of a printing circuit on a substrate for obtaining an electric connection state. Accordingly, the elastic contact piece 134 is always in the state of elastically displaced toward the terminal bottom plate 136 side when it is contacted with a counterpart conductor portion.
In the connecting operation of the connecting terminal 131 with the above-mentioned configuration, a counterpart conductor portion guided by the front end fold back portion 135 and the connector housing (not illustrated) from the front side or from above while forcing the elastic contact piece 134 is surface-contacted. At the time, the elastic contact piece 134 and the front end fold back portion 135 are deflected so as to force the counterpart conductor portion for achieving the electric connection.
Then, in the case the elastic contact piece 134 is deflected excessively due to external force such as vibration in the state in which the counterpart conductor portion is contacted with the elastic contact piece 134, the lower surface of the elastic contact piece 134 comes in contact with the deflection preventing pieces 139 so that the excessive deflection is regulated.
However, since a specific portion comes in contact with the deflection preventing pieces 139 repeatedly in the conventional connecting terminal 131, a problem is involved in that the contacting portions are deteriorated or flawed so as to ruin a good connection state.
Moreover, since the elastic contact piece 134 comes in contact with the deflection preventing pieces 139 vigorously so as to be plastically deformed if an external force larger than the tolerable limit is applied, a problem is involved in that a good connection state with the counterpart conductor portion cannot be ensured.